In the ebb and flow of surface ships and submarines at Pearl Harbor, the tide is currently going out.

The guided-missile destroyer USS Paul Hamilton, a Hawaii stalwart since its commissioning in 1995, pulled away from pier Bravo 25 at 9:09 a.m. Tuesday for a home-port switch to San Diego and dry-docking and maintenance there.

The USS Chosin, meanwhile, the second-to-last cruiser at Pearl Harbor, departed March 25 after 25 years in Hawaii for modernization and its new home port in San Diego.

Two aging Los Angeles- class submarines, the USS City of Corpus Christi and USS Houston, are expected to be retired in late May and early June in Pearl Harbor.

The changes will mean 19 nuclear attack subs remain at Pearl — still the most of any base in the Navy — while surface ships now have dropped to nine.

Navy officials emphasized that Pearl Harbor still has a robust fleet within the “re-balance” to the Pacific, but the Navy has fewer ships overall and, according to defense experts, too many responsibilities worldwide.

Capt. Eric Weilenman, chief of staff of Naval Surface Group Middle Pacific, said it’s normal for the Pearl Harbor fleet to fluctuate and that it’s “part of the challenge of maintenance and modernization versus new ship construction and finding the right balance on where that makes sense.”

In the fiscally constrained environment, some hard choices have to be made about where the Navy is going to re-balance the fleet, he said.

“Make no mistake, there’s still re-balance to the Pacific because we recognize that that’s where most of our threat is,” Weilenman said before the Paul Hamilton departed. “So in the near term it may appear as though we’re down a little bit in terms of ships here at Pearl, and that’s true. We’re going to be down to nine here for the short term. But we’re going to come back up to 10 when the William P. Lawrence comes out here later on.”

The Lawrence, a destroyer, was in South Korea last month as part of a seven-month deployment by the USS John C. Stennis carrier strike group that started in January.

The destroyer USS Daniel Inouye, now under construction, also will be based at Pearl Harbor.

The changes come as the Center for Strategic and Budgetary Assessments reported in November that the Navy and Marine Corps are at a tipping point because they are deploying beyond their means. Ready naval forces are too small to meet the needs of combatant commanders.

BETWEEN 1998 and 2014 the number of ships deployed overseas remained at about 100. But the fleet shrank by about 20 percent, and as a result, “each ship is working harder to maintain the same level of presence,” CSBA said.

CSBA said the Navy and Marine Corps are facing a fundamental choice: maintain current levels of forward presence and risk over-stressing the force, or reduce presence and restore readiness through adequate training, maintenance and time at home.

Weilenman said the Navy also is increasing capability with ships such as the Pearl Harbor destroyer USS John Paul Jones, which has the latest integrated air and ballistic missile defense.

Cmdr. Brook DeWalt, a spokesman for the U.S. Pacific Fleet submarine force at Pearl Harbor, said that “Hawaii is a strategically important location, obviously, and it has historically been our large submarine base.”

That’s not likely to change.

“I can’t speak to numbers, but we expect to maintain a robust presence here at Pearl Harbor,” DeWalt said. Newer Virginia-class submarines continue to arrive, but retirements of older Los Angeles-class subs are outpacing new construction.

The Congressional Research Service said Thursday that the Navy wants to achieve a fleet of 308 ships in coming years, including 48 attack submarines, but the total could dip to 41 subs in fiscal 2029.

Aboard the Paul Hamilton on Tuesday, the ship’s crew of about 300 was more concerned with a new home in San Diego.

But Senior Chief Nixon Galan, who’s spent 25 years in the Navy in Hawaii, and the last three on the Paul Hamilton, said he’s coming back.

“After being in Hawaii for 25 years, (I have) mixed emotions, mixed feelings,” said Galan, 48. “My family is staying behind (in Hawaii). The only thing is that I’m from (Los Angeles). So I get a chance to commute back and forth and spend time with my parents.”

But he also is going to be retiring and returning to Hawaii in late summer. “We love it here,” Galan said.